1. Field of the Invention
The present invention relates to a method and apparatus for producing a disposable worn article.
2. Description of the Related Art
During the process of producing a worn article, a semi-finished product thereof, e.g., a web, is sometimes folded in two. An example of such an operation is disclosed in U.S. Pat. No. 3,828,367. When a web is folded in two, it is ideally folded with the edges on both sides being aligned with each other. However, it is typically difficult to fold a web in such a manner.
The misalignment between the opposite side edges of the web occurs because the web is carried while deviating toward either side with respect to the running direction, i.e., because the center line of the web is shifted to the left or to the right.
The present inventors have conducted research on the possible causes of such a shift, and found that it occurs for the following reasons:
(1) The opposite side edges of the web are under different tensions. Particularly, where an elastic member is placed on the web, the difference between the tensions on the opposite side edges may be significant.
(2) Where an absorbent is placed on the web, the thickness of the web to be folded differs among different positions thereof along the running direction.